For computing spectra we use tSurff with radius \(R_c=35\) , which implies that beyond that radius all effects of the
molecular potential are neglected [1]}, [2]}. The cutoff is well beyond the
\(C-O\)  bond distance of \(2.197\,au\) , such that we are in the Coulombic tail of
the molecular potential and safely outside the reach of any occupied orbital \(\varphi _c\) .
Note that absolute delays between Coulomb and free motion cannot be defined,
as these diverge logarithmically with the propagation distance.
Rather, in our comparisons we assess the effects at short- and medium range interactions, where “medium range” means
distances where non-Coulombic contributions to the potential would be well-approximated by multipole potentials.
